ACT · Coordinate Geometry · Lines, slopes, and intercepts
Question act-q-00398
Hard Multiple choice No calculator
The question
What is the slope of the line passing through (5, 4) and (2, -4)?
- 0.38
- 2.67
- 3.17
- -2.67
Show answer & worked solution
Answer: 2.67
Worked solution. Slope = (y₂ − y₁) / (x₂ − x₁) = (-4 − 4) / (2 − 5) = -8 / -3 = 2.67.
Why each wrong choice is wrong. Reversing the subtraction order in the numerator without doing the same in the denominator gives the negative of the slope — a common slip.
Test-day tactic. Pick which point is (x₁, y₁) and which is (x₂, y₂) before computing, and stick with the choice. The order doesn't matter as long as it's consistent.
About this question type
Items test the slope formula, the slope-intercept and point-slope forms, and the slope rules for parallel (equal) and perpendicular (negative reciprocal) lines.
You will see a question shaped like this one on roughly every other official ACT form, typically at the back end of the section, where the score gradient is steepest. Treat any miss in this subtopic as a signal to drill the subtopic page before you do another full practice test.